JPH0329133A - Optical information recording medium - Google Patents

Abstract

PURPOSE:To improve recording sensitivity by forming guide grooves deeper than the thickness of a recording layer in order to reduce thermal diffusion from the recording film when the film is irradiated with light spot. CONSTITUTION:A substrate 1 comprising polycarbonate or UV-curing resin has guide grooves 1 of rectangular cross section, on which a dielectric film 3 such as AlN, magneto-optical film 4, dielectric film 5 of AlN and a metal film 6 of Au are formed. The guide groove is made deep with large taper angle to have a rectangular cross section. Thereby, the recording film on the tapered part can be made thin, which reduces diffusion of heat and raises the temp. of land area. Thus, recording can be performed with low recording power, which improves the recording sensitivity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical recording medium that records and reproduces information using laser light. [Prior art] The guide groove of a conventional optical disc substrate is disclosed in Japanese Patent Application Laid-Open No. 62-223.
As described in Publication No. 837, the optical depth at which the tracking signal is maximum is determined by the wavelength of the incident light λ. The refractive index of the substrate is n.
, it was λ/8n.

In addition, the recording body formed on the optical disc substrate is
As described in No. 0-195751, it was composed of an M electric film, a recording film, a dielectric film, a metal film, etc. [Problem to be solved by the invention] Information signals are recorded by focusing light from a light source on a lens and irradiating it onto a recording film, where the film absorbs the light and becomes heated to a certain temperature. will be carried out. If this heat diffuses widely within the recording film, the temperature will drop and more recording power will be required to perform recording. In the conventional technology, no consideration was given to the diffusion of heat in the recording film, and there was a problem in that more recording power was required. Conventional guide grooves have a ■ shape or a trapezoidal shape with a taper angle of 40 to 60". Note that the membrane is continuously shaped into a land part, a tapered part, and a guide groove. For example, When recording is performed on the recording film, the heat in the recording film diffuses from the land portion to the tapered portion, the guide groove, etc.There is a problem in that the recording sensitivity decreases due to the diffusion of this heat. , the purpose of the present invention is to improve the recording sensitivity. [Means for Solving the Problems] In order to achieve the above object, the present invention has deep guide grooves.
This is a larger Taber angle. The guide groove is also rectangular in shape. When recording is performed on the land, the heat from the land spreads to the tapered part. However, if the guide groove is made deeper, the Taber angle becomes larger, so the thickness of the recording film attached to the Taber part can be made thinner. As the film thickness becomes thinner, the diffusion of heat becomes smaller, so there is less heat diffusion to the tapered area, and the temperature of the land area rises more easily, allowing recording with low recording power. Therefore, recording sensitivity can be improved. Also, if the guide is rectangular,
The record stains attached to the tabular part are either very thin or barely noticeable. Further, the recording film formed on the land comes into contact with the protective film (or adhesive waste) formed thereon. Keep it! The conductivity of the i-film is much lower than that of the recording film. Therefore, the heat in the land portion is hardly diffused into the tapered portion or the protective film, improving recording sensitivity. The guide groove has a function of highly accurate tracking during recording, reproduction, and erasing. The magnitude of the tracking signal from the guide groove is related to the depth d of the guide groove. The refractive index of the disk substrate is n,
When the wavelength of the light source is λ, the condition for the maximum tracking signal is λ d=(2m+1)−8 nm m is a positive integer not including 0. By setting the guide groove to a depth that satisfies the above conditions, it becomes possible to obtain an optical information recording medium that is highly sensitive and obtains a good tracking signal. Further, even if the depth of the guide groove is 8n20, it is possible to obtain an optical information recording medium with virtually no problems. [Example] Example 1 Hereinafter, an example of the present invention will be explained with reference to FIG. In FIG. 1, reference numeral 1 denotes a substrate made of polycarbonate, ultraviolet curing resin, etc., on which a rectangular guide groove 2 is formed. The depth of the guide groove 2 is 210 nm. and,
On this substrate 1, an rttt body film 3 such as AiN is formed. The thickness of this m-electrode absorber 3 is 75 nm. On the dielectric film 3, a Tbl'aCo magneto-optical film [4] was formed. The magneto-optical film thickness is 20 nm. On the magneto-optical film 4, AIN
The II electric material film 5 and the Au metal film 6 are each 40 nm thick.
A thickness of 30 nm was formed. When information was recorded on such a substrate, the sensitivity improved by approximately 20%. Embodiment 2 In FIG. 2, 11 is a trapezoidal guide 4 with a high Taber angle.
12 is formed on a substrate made of polycarbonate, ultraviolet curing resin, etc. The depth of the guide groove 12 is 210n
It is m. On this substrate 11 is a dielectric material wA3 made of SiN film.
It took shape. The film thickness of this dielectric 3 is 80 nm. A magneto-optical film 4 of GdFeCo was formed on the dielectric film 3. The magneto-optical film thickness is 20 nm. On the magneto-optical film 4, S
Dielectric material 1i11i5 of iN and metal film 6 of ゛l'i
were formed to a thickness of 30 nm and 50 nm, respectively.
When information was recorded on such a substrate, the sensitivity improved by approximately 15%. [Effects of the Invention] According to the present invention, by making the guide groove deeper than the thickness of the recording medium, it is possible to reduce the diffusion of heat from the recording film when the light spot is irradiated, so that the recording sensitivity can be significantly improved.

[Brief explanation of drawings]

1 and 2 are cross-sectional views showing the structure of the optical information recording medium of the present invention.

Claims (1)

[Scope of Claims] 1. A recording medium for recording and reproducing information bits, characterized in that a guide groove formed on the disk substrate is deeper than a laminated recording film. 2. The depth d of the guide groove is nd=(λ/8)(2m+1) (where m is an integer of 1 or more), where λ is the reproduction light source wavelength and n is the refractive index of the substrate. A recording medium according to claim 1. 3. The recording medium according to claim 1, wherein the recording film is a magneto-optical recording medium comprising an inorganic film or a magnetic film. 4. The recording medium according to claim 1, wherein the recording film includes a metal film.